Will predators attack your swallows?There's always danger of predation, so protecting your nesting birds is a crucial responsibility for you as a nest box project manager. Finding boxes emptied of eggs or young, or discovering discarded wings, legs and clumps of feathers below a box is terribly disheartening. Please take steps to reduce chances of predation. Careful choice of project site and proper location of boxes will limit risk of predators finding your boxes, but you should also try to prevent predators from reaching any boxes they do happen to discover.

What animals predate nesting Tree Swallows?

Raccoons, cats, and opossums will kill and eat any adults and young they can pull out of boxes.

Raccoons are especially dangerous because if they find one box and can predate it, they look for other boxes and may predate every box in a project.

Squirrels are also important predators of cavity-nesting bird eggs and young, and if box entrances are too small squirrels can chew their way in. And chipmunks, though cute, predate more bird nests than most people realize. Photo below by Barry Scully.

Weasels are so slender they can enter most boxes they can reach. The photo below of a Short-tailed Weasel exiting a predated box is by Barbara Russell.

Most snakes can't climb poles, but a few species can, and will enter boxes to eat eggs, young or adults trapped inside.

How can you stop predators from reaching boxes?

Make it difficult and unpleasant! The best method is to attach a predator guard to the pole below the box.

You should use a guard on every box because raccoons and climbing snakes can get up even thin metal poles surprisingly easily, as the photo below taken during experiments conducted by bluebird expert Keith Kridler demonstrates.

Conical and Stovepipe Guards (see below) are somewhat effective, but they can be expensive to make and very expensive to buy.

Hardware Screen Guards that project out around the entrance hole are less expensive, but they make it difficult and time-consuming for adult swallows to access nests when feeding nestlings. (Note the overlarge hole and small dimensions of the box below, obviously not a good design for Tree Swallows).